Extremes of moisture availability reconstructed from tree rings for recent millennia in the great basin of western north America

Abstract

The western USA, from the eastern slopes of the Rocky Mountains to the Pacific Ocean, is rich in tree-ring archives of climate variability. We make particular reference to tree rings from the long-lived conifers of the high mountains of the Great Basin. These are among the few tree-ring records in the world likely to yield reliable information on not only interannual and interdecadal time scales, but also century scale change, since thousand-year and older trees growing at low density in open stands are relatively common in this region. These records have yielded well-verified reconstructions of precipitation which contain evidence on all time scales of extremes more intense or more persistent than those known for the twentieth century. The implications of these findings for forests are discussed.